Thousands left without power after storm sweeps through Sydney

Thousands of homes in Sydney have had a night without power after a severe storm and damaging winds ripped through the city, bringing trees crashing down on power lines, houses and cars.

It's likely those residents hit by the blackout in Mount Druitt, Castle Hill and Parramatta will remain without electricity until this afternoon with crews scrambling to clean-up and repair the damage caused by the storm.

Western Sydney and the Hills District were the worst hit with lightning and strong winds cutting power to 33,000 properties at the peak of the storm.

Endeavour Energy was calling customers with registered life support equipment to check on their welfare.

In Sydney's north 800 homes in Berowra, 1300 in the Central Coast suburbs of Woy Woy and 400 in Saratoga were without power yesterday evening.

Those residents were expected to have had their electricity restored by midnight, an Ausgrid spokeswoman told AAP.

Trains and flights were delayed, while commuters heading home experienced traffic chaos after trees fell onto power lines.

Wind gusts reached 57km/h in Penrith and 85km/h at Cowra in the central west and Goulburn in the southern tablelands.

Fallen trees affected roads in a number of areas across western Sydney, including in St Marys, where two of three westbound lanes of the Great Western highway were closed for some time after a tree fell onto power lines.